The Efficient Home Forum

I installed the evohome sytem about six months ago. All bar a few radiators have the evohome wireless valves on them and the BD91 is connected to my combi boiler. This BD91 is set as the boiuler controller, but my boiler has a permeanat live as well. It works fantastic. I am having a single zone wet underfloor heating system fitted. In fact it has been fitted, but not yet wired into the evohome system. The plumber tells me he has made an s plan system and now there is a motorised valve on the radiator system and another on the underfloor system. These are both new and weren't there before. The underfloor system also has its own pump. I was told, and have purchased another BD91 and a wireless room stat to control the underfloor part.

The question is how do I now wire up and configure the new system? The radiator part needs to open the valve and turn on the boiler when the rad stats call for heat. When the underfloor stat calls for heat it needs to alo open the valve and switch on the pump.

Any help greatly appreciate. Despite having this great and expensive new kitchen fitted the thing I am most nervous about is getting the evohome to work as its such a great system.

Chris

Hi Chris,

What you are suggesting isn't possible with evohome and your installer has not followed the schematic at the back of the installation guide (page 43).

What should have been done, is the radiator circuit fitted with HR92's on all radiators and then the zone valve and the pump on the UFH circuit controlled by the BDR91. No motorised zone valves should have been fitted on the radiator circuit, as this cannot be supported.

I hope this helps.

Thanks,

Richard

Thanks Richard,

So if the valve is removed from the radiator circuit it should work.

I have a couple radiators (bathrooms) without radiator valves, which at the moment just warm up whenever the system calls for heat. Is it a problem to have these without valves?

Thanks.

Chris.

Richard, you are referring to the bottom picture on page 43?

Instead of stored hot water it's underloor heating?

Thanks.

Chris.

Yep, remove the valve from the radiator circuit... If you have open circuit radiators then these will come on with UFH too, but not end of the world if this is happening already with radiator demand.

The Page 43 Figure 4 diagram shows how evohome controls the system in a perfect evohome system. This is zone valveless on the radiator circuit, with HR92's. If you have hot water then it is done like depicted, if you dont then don't...

Richard,

Thank you very much for the help. I think I get it now. I leave the current BDR91 as is. Remove the radiator heating system motorised valve. Set the NEW BDR91 to turn on the UF pump and open the valve (set as a zone valve in the evohome system) and pair to the new wireless room stat.

Fingers crossed.

Chris